CVE-2026-3849: Buffer Overflow in HPKE via Oversized ECH Config
Stack Buffer Overflow in wcHpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2026-3849?
CVE-2026-3849 has been classified as a high severity vulnerability due to the potential for remote code execution from a stack buffer overflow.
How do I fix CVE-2026-3849?
To fix CVE-2026-3849, update the wolfSSL library to version 5.8.5 or later where the buffer overflow vulnerability is addressed.
Who is affected by CVE-2026-3849?
CVE-2026-3849 affects users of wolfSSL version 5.8.4 that implement the Encrypted Client Hello support.
What components are impacted by CVE-2026-3849?
CVE-2026-3849 impacts the hpkeLabeledExtract function within the wolfSSL library, specifically related to ECH configuration processing.
Can CVE-2026-3849 be exploited remotely?
Yes, CVE-2026-3849 can be exploited remotely if an attacker can send a maliciously crafted ECH config to a vulnerable client.